Lecture 14 - Neuromuscular adaptations to exercise training Flashcards
What are the NM goals of training?
Enhance musculoskeletal health
Improve sports performance
Change body aesthetics
What are some NM adaptation to training for a) elderly populations, b) populations following immobilisation or injury and c) for people with T2DM?
a) Develop appropriate muscle mass for health: for functional activities
b) Countermeasure to muscle atrophy & weakness: following immobilisation, injury, bedrest
c) Enhance muscle metabolism: diabetes management and T2DM prevention
Whare are some NM adaptations to training with regards to muscle performance?
- Strength
- Muscle endurance
- Muscle power
- Flexibility
- Posture
- Running/movement efficiency?
What are some equipment used in resistance training?
Free weights, pulleys/cams, resistance bands, body weight*
What is the typical %age increase in strength/peak torque with resistance training?
25-30% increases typical with resistance training
Of males and females, which population experiences higher relative increases in strength
Similar relative increases (% change) in M & F
What specific adaptation suggests that training causes both neural and morphological changes?
a) Rate of change in strength is much greater than can be accounted for by changes in muscle size
b) Larger increase in dynamic strength compare to relative isometric strength
* Suggests motor skill/learning effects (i.e., neural)
What is a crossover effect in regards to resistance training?
Train one leg, can get improvements in other leg
What neural adaptations do we observe and how does this change subsequent muscular force?
MOTOR UNIT RECRUITMENT PATTERNS: greater efficiency & specificity of recruitment.
MOTOR UNIT SYNC: increase the sync for maximal and near efforts, decrease for submax activity.
DEC. CENTRAL INHIBITION FOR VOLUNTARY EFFORTS: decrease the effects of agonist activation.
Does muscle force increases with increases in muscle size
Yes
How is muscle size and strength impacted over a period of consistent resistance training?
- After ~8 weeks training, increases in strength track with muscle size
- Size increases continue for at least 12 months in most studies
What morphological changes impact the magnitude of changes on muscle size?
- Different usual usage (i.e., responsiveness: lower initial fitness)
- Different androgen receptor density
Which fibres have a higher capacity to increase in size
Type II
What are the upper limb differences in muscle size between males and females?
Upper limb: size increases more in M than F
How does muscular hypertrophy occur at the cellular level?
- Increase size of fibres (bigger fibres)
- Increase myofibril size & number
(myoblasts fuse to form myotubes and then develop myofibrils within them - hypertrophy)
What is the distinction between muscular hypertrophy and hyperplasia?
Hypertrophy can increase the number of myofibrils within a cell, where as hyperplasia refers to increases in the number of muscle fibres themselves
What is once cause of limited flexibility and how can a certain morphological change increase flexibility?
- One cause of limited flexibility (i.e., range of motion around a joint) is lack of length in muscle
- Insertion of more sarcomeres in fusiform muscles could increase muscle length: stretching and eccentric training
- Evidence unclear
What is the relation between myofibril content and myonuclei? Why is this the case?
- The number of myonuclei within a muscle fiber is proportional to its myofibril content
- In general, fast-twitch or Type II muscle fibers tend to have a higher myofibril content per nucleus compared to slow-twitch or Type I muscle fibers. This means that Type II muscle fibers typically contain more myofibrils per nucleus, allowing them to generate greater force and power compared to Type I fibers.
What is ‘muscle memory’ and how does it occur in an atrophied muscle after a period of detraining
Muscle regeneration occurs after a sufficient stimulus. The steps involved include an inflammatory response and myoblasts proliferating and differentiating to repair the damaged fibre. Ultimately, more myonuclei are added to the muscle. When atrophy occurs, changes in myonuclei do not. This ‘shortcuts’ hypertrophy when retraining a muscle due to the presence of additional myonuclei acquired during previous muscle growth. These additional myonuclei can contribute to a faster and more robust hypertrophic response compared to initial muscle growth.
What are some morphological changes that occur to tendons in response to resistance training?
– Tendon stiffness
– Tendon hypertrophy
What are some morphological changes that occur to the pennation of muscle in response to resistance training?
May increase to 45deg with HRST (most optimal angle for strength)
What is the AoP for muscles in untrained individuals usually?
< 45deg
What are the rates of change for neurological and morphological adaptations in response to strength training?
- Neural changes occur rapidly
- Hypertrophy changes continue over longer time frames
